Abstract

BACKGROUND Previous clinical studies showing that cinnamon spice lowers blood glucose concentrations had inconsistent results. OBJECTIVES To determine the effect of daily cinnamon spice supplementation in an amount commonly used for seasoning on glucose concentrations in adults with obesity and prediabetes. METHODS Following a 2-wk run-in period of maintaining a low polyphenol/fiber diet, 18 participants with obesity and prediabetes underwent a 10-wk randomized, controlled, double-blind, crossover trial (mean age 51.1 y; mean fasting plasma glucose 102.9 mg/dL). The participants were randomly assigned to take cinnamon (4 g/d) or placebo for 4-wk, followed by a 2-wk washout period, and then crossed over to the other intervention for an additional 4-wk. Glucose changes were measured with continuous glucose monitoring. Oral glucose tolerance testing immediately following ingestion of cinnamon or placebo was performed at 4-time points to assess their acute effects both at the baseline and end of each intervention phase. Digestive symptom logs were obtained daily. RESULTS There were 694 follow-up days with 66,624 glucose observations. When compared with placebo, 24-h glucose concentrations were significantly lower when cinnamon was administered [mixed-models; effect size (ES) = 0.96; 95 % confidence interval (CI): -2.9, -1.5; P < 0.001]. Similarly, the mean net-area-under-the-curve (netAUC) for glucose was significantly lower than for placebo when cinnamon was given (over 24 h; ES = -0.66; 95 % CI: 2501.7, 5412.1, P = 0.01). Cinnamon supplementation resulted in lower glucose peaks compared with placebo (Δpeak 9.56 ± 9.1 mg/dL compared with 11.73 ± 8.0 mg/dL; ES = -0.57; 95 % CI: 0.8, 3.7, P = 0.027). Glucose-dependent-insulinotropic-polypeptide concentrations increased during oral glucose tolerance testing + cinnamon testing (mixed-models; ES = 0.51; 95 % CI: 1.56, 100.1, P = 0.04), whereas triglyceride concentrations decreased (mixed-models; ES = 0.55; 95 % CI: -16.0, -1.6, P = 0.02). Treatment adherence was excellent in both groups (cinnamon: 97.6 ± 3.4 % compared with placebo: 97.9 ± 3.7 %; ES = -0.15; 95 % CI: -1.8, 0.2, P = 0.5). No differences were found in digestive symptoms (abdominal pain, borborygmi, bloating, excess flatus, and stools/day) between cinnamon and placebo groups. CONCLUSIONS Cinnamon, a widely available and low-cost supplement, may contribute to better glucose control when added to the diet in people who have obesity-related prediabetes. This trial was registered at clinicaltrials.gov as NCT04342624.

Abstract

In recent years, an increasing trend has been observed in the consumption of specific polyphenols, such as flavonoids and phenolic acids, derived from green tea, berries, and other similar sources. These compounds are believed to alleviate oxidative stress and inflammation resulting from exercise, potentially enhancing athletic performance. This systematic review critically examines the role of polyphenol supplementation in improving aerobic endurance among athletes and individuals with regular exercise habits. The review involved a thorough search of major literature databases, including PubMed, Web of Science, SCOPUS, SPORTDiscus, and Embase, covering re-search up to the year 2023. Out of 491 initially identified articles, 11 met the strict inclusion criteria for this review. These studies specifically focused on the incorporation of polyphenols or polyphenol-containing complexes in their experimental design, assessing their impact on aerobic endurance. The methodology adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and the risk of bias was evaluated using the Cochrane bias risk assessment tool. While this review suggests that polyphenol supplementation might enhance certain aspects of aerobic endurance and promote fat oxidation, it is important to interpret these findings with caution, considering the limited number of studies available. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42023453321.

Abstract

BACKGROUND Exercise and the consumption of sugars result in a dysfunction of the intestinal barrier (IB). Here, we determined the effect of sugar in a natural matrix on the intestinal barrier after moderate (A) and intensive endurance exercise (B). METHOD The IB function was determined before (pre) and after running (post), and 120 and 180 min after consuming the drink by measuring serum endotoxin concentrations (lipopolysaccharides-LPS), IL-6, CD14, and i-FABP. In study A, nonspecifically trained participants (n = 24, males and females, age 26 ± 4) ran for one hour at 80% of their individual anaerobic threshold (IAT). After finishing, the runners consumed, in a crossover setup, either 500 mL of water, diluted cloudy apple juice (test drink), or an identical drink (placebo) without the fruit juice matrix (FJM). In study B, the participants (n = 30, males and females, age 50 ± 9) completed an ultra-marathon run, were divided into groups, and consumed one of the above-mentioned drinks. RESULTS Study A: Exercise resulted in a significant increase in serum LPS, i-FABP, and IL-6, which decreased fast after finishing. No impact of the different drinks on LPS i-FABP, or IL-6 could be observed, but there was an impact on CD14. Study B: The ultra-marathon resulted in a strong increase in serum LPS, which decreased fast after finishing in the water and test drink groups, but not in the placebo group. CONCLUSIONS The consumed drinks did not affect the kinetics of IB regeneration after moderate exercise, but impacted CD14 serum concentrations, indicating possible beneficial effects of the FJM on the immune system. After an ultra-marathon, IB function regenerates very fast. The intake of sugar (placebo) seems to have had a negative impact on IB regeneration, which was diminished by the presence of the FJM.

Abstract

BACKGROUND Liver cancer is one of the common malignancies. The dysregulation of metabolism is a driver of accelerated tumourigenesis. Metabolic changes are well documented to maintain tumour growth, proliferation and survival. Recently, a variety of polyphenols have been shown to have a crucial role both in liver disease prevention and metabolism regulation. METHODS We conducted a literature search and combined recent data with systematic analysis to comprehensively describe the molecular mechanisms that link polyphenols to metabolic regulation and their contribution in liver protection and liver cancer prevention. RESULTS Targeting metabolic dysregulation in organisms prevents and resists the development of liver cancer, which has important implications for identifying new therapeutic strategies for the management and treatment of cancer. Polyphenols are a class of complex compounds composed of multiple phenolic hydroxyl groups and are the main active ingredients of many natural plants. They mediate a broad spectrum of biological and pharmacological functions containing complex lipid metabolism, glucose metabolism, iron metabolism, intestinal flora imbalance, as well as the direct interaction of their metabolites with key cell-signalling proteins. A large number of studies have found that polyphenols affect the metabolism of organisms by interfering with a variety of intracellular signals, thereby protecting the liver and reducing the risk of liver cancer. CONCLUSION This review systematically illustrates that various polyphenols, including resveratrol, chlorogenic acid, caffeic acid, dihydromyricetin, quercetin, catechins, curcumin, etc., improve metabolic disorders through direct or indirect pathways to protect the liver and fight liver cancer.

Abstract

Blueberries beneficially modulate physiologic mechanisms relevant to the pathogenesis of functional gastrointestinal disorders (FGID). Forty-three patients with FGID received freeze-dried blueberries (equivalent to 180 g fresh blueberries) or sugar and energy-matched placebo in a double-blind, randomized, cross-over study. After 6 weeks of treatment, the differences in Gastrointestinal Clinical Rating Scale (GSRS) scores and abdominal symptom relief were compared as primary outcome measures. The quality of life and life functioning ratings (OQ45.2 questionnaire), Bristol stool scales, and fructose breath test results constituted secondary outcome measures. Blueberry treatment resulted in more patients with relevant abdominal symptom relief compared to placebo (53% vs. 30%, p = 0.03). Total and pain GSRS scores improved insignificantly (mean treatment differences [95% CI]: -3.4 [-7.4 to 0.6] (p = 0.09) and -1.0 [-2.2 to 0.1] (p = 0.08), respectively). OQ45.2 scores improved during blueberry treatment compared to placebo (treatment difference -3.2 [95% CI: -5.6 to -0], p = 0.01). Treatment effect differences for the further measures did not reach statistical significance. Blueberries relieved abdominal symptoms and improved general markers of well-being, quality of life, and life functioning more than placebo in patients with FGID. Consequently, the polyphenol and fiber components of blueberries exert broad beneficial effects separate from the sugars present in both treatments.

Abstract

Osteoporosis is a condition favored by the postmenopausal decline in estrogen levels and worsened by oxidative stress (OS). Polyphenols are natural compounds abundantly found in fruits and vegetables, and they exert antioxidant and hormonal effects that could be useful in osteoporosis prevention, as suggested by epidemiological studies showing a lower incidence of fractures in individuals consuming polyphenol-rich diets. The aim of our meta-analysis is to evaluate the effects of polyphenols on bone mineral density (BMD, primary endpoint) and bone turnover markers (BTMs, secondary endpoint) in postmenopausal women. Twenty-one randomized control trials (RCTs) were included in our analysis after in-depth search on PubMed, EMBASE, and Scopus databases. We found that supplementation with polyphenols for 3-36 months exerted no statically significant effects on BMD measured at lumbar spine (sMD: 0.21, 95% CI [-0.08 to 0.51], p = 0.16), femoral neck (sMD: 0.16, 95% CI [-0.23 to 0.55], p = 0.42), total hip (sMD: 0.05, 95% CI [-0.14 to 0.24], p = 0.61), and whole body (sMD: -0.12, 95% CI [-0.42 to 0.17], p = 0.41). Subgroup analysis based on treatment duration showed no statistical significance, but a significant effect on lumbar BMD emerged when studies with duration of 24 months or greater were analyzed separately. On the other hand, we found a significantly slight increase in bone-specific alkaline phosphatase (BALP) levels (sMD: 1.27, 95% CI [1.13 to 1.42], p < 0.0001) and a decrease in pyridinoline (PD) levels (sMD: -0.58, 95% CI [-0.77 to -0.39], p < 0.0001). High heterogeneity among studies and unclear risk of bias in one third of the included studies emerged. A subgroup analysis showed similar effects for different duration of treatment and models of dual-energy X-ray absorptiometry (DXA) scanner. More robust evidence is needed before recommending the prescription of polyphenols in clinical practice.

Abstract

OBJECTIVE The aim of this study is to evaluate the effectiveness and safety of curcumin in rheumatoid arthritis patients. METHODS A computerized search from PubMed, Embase, Cochrane Library, and Web of Science databases was performed until 3 March 2023. Literature screening, basic data extraction and risk of bias evaluation were independently performed by two researchers each. The quality evaluation of the literature was performed according to the Cochrane Handbook for Risk of Bias Assessment tool for treatment evaluation. RESULTS The current study includes six publications covering 539 rheumatoid arthritis patients. The activity of rheumatoid arthritis was assessed using erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), protein, disease activity score (DAS), rheumatoid factor (RF), Visual Analogue Scale (VAS) pain, tender joint count (TJC) and swollen joint count (SJC). ESR (MD = -29.47, 95% CI [-54.05, -4.88], Z=2.35, P = 0.02), DAS28 (MD = -1.20, 95% CI [-1.85, -0.55], Z=3.62, P = 0.0003), SJC (MD = -5.33, 95% CI [-9.90, -0.76], Z = 2.29, P = 0.02) and TJC (MD = -6.33, 95% CI [-10.86, -1.81], Z = 2.74, P = 0.006) showed significantly change in experimental patients compared with controls. CONCLUSION Curcumin is beneficial for rheumatoid arthritis treatment. Inflammation levels and clinical symptoms in patients with rheumatoid arthritis can be improved by curcumin supplementation. Large sample randomized controlled trials on the effects of curcumin on patients with rheumatoid arthritis are needed in the future. SYSTEMATIC REVIEW REGISTRATION https://www.crd.york.ac.uk/PROSPERO/, identifier (CRD42022361992).

Abstract

BACKGROUND AND AIMS Polyphenol-rich foods have beneficial properties that may lower cardiometabolic risk. We aimed to prospectively investigate the relationship between intakes of dietary polyphenols, and metabolic syndrome (MetS) and its components, in 676 Danish residents from the MAX study, a subcohort of the Danish Diet, Cancer and Health-Next Generations (DCH-NG) cohort. METHODS AND RESULTS Dietary data were collected using web-based 24-h dietary recalls over one year (at baseline, and at 6 and 12 months). The Phenol-Explorer database was used to estimate dietary polyphenol intake. Clinical variables were also collected at the same time point. Generalized linear mixed models were used to investigate relationships between polyphenol intake and MetS. Participants had a mean age of 43.9y, a mean total polyphenol intake of 1368 mg/day, and 75 (11.6%) had MetS at baseline. Compared to individuals with MetS in Q1 and after adjusting for age, sex, lifestyle and dietary confounders, those in Q4 - for total polyphenols, flavonoids and phenolic acids-had a 50% [OR (95% CI): 0.50 (0.27, 0.91)], 51% [0.49 (0.26, 0.91)] and 45% [0.55 (0.30, 1.00)] lower odds of MetS, respectively. Higher total polyphenols, flavonoids and phenolic acids intakes as continuous variable were associated with lower risk for elevated systolic blood pressure (SBP) and low high-density lipoprotein cholesterol (HDL-c) (p < 0.05). CONCLUSIONS Total polyphenol, flavonoid and phenolic acid intakes were associated with lower odds of MetS. These intakes were also consistently and significantly associated with a lower risk for higher SBP and lower HDL-c concentrations.

Abstract

BACKGROUND Evidence suggests that the intake of blueberry (poly)phenols is associated with improvements in vascular function and cognitive performance. Whether these cognitive effects are linked to increases in cerebral and vascular blood flow or changes in the gut microbiota is currently unknown. METHODS A double-blind, parallel randomized controlled trial was conducted in 61 healthy older individuals aged 65-80 y. Participants received either 26 g of freeze-dried wild blueberry (WBB) powder (302 mg anthocyanins) or a matched placebo (0 mg anthocyanins). Endothelial function measured by flow-mediated dilation (FMD), cognitive function, arterial stiffness, blood pressure (BP), cerebral blood flow (CBF), gut microbiome, and blood parameters were measured at baseline and 12 wk following daily consumption. Plasma and urinary (poly)phenol metabolites were analyzed using microelution solid-phase extraction coupled with liquid chromatography-mass spectrometry. RESULTS A significant increase in FMD and reduction in 24 h ambulatory systolic BP were found in the WBB group compared with the placebo group (0.86%; 95% CI: 0.56, 1.17, P < 0.001; -3.59 mmHg; 95% CI: -6.95, -0.23, P = 0.037; respectively). Enhanced immediate recall on the auditory verbal learning task, alongside better accuracy on a task-switch task was also found following WBB treatment compared with placebo (P < 0.05). Total 24 h urinary (poly)phenol excretion increased significantly in the WBB group compared with placebo. No changes in the CBF or gut microbiota composition were found. CONCLUSIONS Daily intake of WBB powder, equivalent to 178 g fresh weight, improves vascular and cognitive function and decreases 24 h ambulatory systolic BP in healthy older individuals. This suggests that WBB (poly)phenols may reduce future CVD risk in an older population and may improve episodic memory processes and executive functioning in older adults at risk for cognitive decline. Clinical Trial Registration number in clinicaltrials.gov: NCT04084457.

Abstract

OBJECTIVES The association between coffee intake and hypertension (HTN) risk is controversial. Therefore, this systematic review and meta-analysis aimed at summarizing the current evidence on the association of coffee with hypertension risk in observational studies. METHODS PubMed/Medline and Web of Science were searched for observational studies up to February 2023. Observational studies which assessed the risk of HTN in the highest category of coffee consumption in comparison with the lowest intake were included in the current meta-analysis (registration number: CRD42022371494). The pooled effect of coffee on HTN was evaluated using a random-effects model. RESULTS Twenty-five studies i.e., thirteen cross-sectional studies and twelve cohorts were identified to be eligible. Combining 13 extracted effect sizes from cohort studies showed that higher coffee consumption was associated with 7% reduction in the risk of HTN (95% CI: 0.88, 0.97; I2: 22.3%), whereas combining 16 effect sizes from cross-sectional studies illustrated a greater reduction in HTN risk (RR = 0.79, 95% CI: 0.72, 0.87; I2 = 63.2%). These results varied by studies characteristics, such as the region of study, participants' sex, study quality, and sample size. CONCLUSIONS An inverse association was found between coffee consumption and hypertension risk in both cross-sectional and cohort studies. However, this association was dependent on studies characteristics. Further studies considering such factors are required to confirm the results of this study.